The present invention relates to an apparatus for drying semiconductor wafers or LCD glass substrates by use of vapor of organic solvent such as an alcohol group, and a method for drying substrates by use of organic solvent vapor.
In the manufacture of a semiconductor device, there is used a wet-type washing/drying system for removing contamination such as particles or organic material from a wafer surface. The wet-type washing/drying system comprises a plurality of washing process tanks and drying process tanks to perform a continuous batch process. Chemicals or pure water is supplied to each washing process tank, and a plurality of wafers are dipped in liquid at one time to be cleaned. On the other hand, vapor of organic solvent such as isopropyl alcohol ((CH.sub.3).sub.2 CHOH, hereinafter called "IPA") is supplied to the drying process tank, so that the plurality of wafers are dried at one time by a function of organic solvent vapor.
In a closed-type washing/drying device, IPA vapor is supplied to the process tank as discharging washing liquid (pure water) from a lower portion of the tank. As a result, the wafers can be dried just after washing. According to this type, since a film of washing liquid (pure water) is removed from the surface of each wafer, a clean dried surface can be obtained without generating a water mark on the wafer surface. In this type of the device, IPA liquid is supplied to a vapor generating chamber from an IPA liquid supply unit to heat IPA liquid and to generate vapor. Then, IPA vapor is introduced to the process tank from the vapor generating chamber.
In this type of the device, since IPA liquid of the vapor generating chamber is consumed, it is necessary to supply IPA liquid to the vapor generating chamber from the IPA liquid supply unit. However, if an inner pressure of the vapor generating chamber is gradually increased by generation of IPA vapor, it is difficult to supply IPA liquid to the vapor generating chamber from the IPA liquid supply unit.
Japanese Patent registration No. 2544971 discloses a washing/drying device in which a fixed amount of organic solvent is dropped on a hot plate of a preliminary chamber to generate a fixed amount of organic solvent vapor, and the fixed amount of solvent vapor is supplied to a main chamber to dry a glass substrate. However, in this device, since the fixed amount of solvent is supplied to the vapor generating chamber for a long period of time during the process, vapor is excessively supplied to the process tank from the vapor generating chamber, and the total amount of consumption of solvent is excessively increased.